Changes in cardiovascular function and related psychophysiological pathways in a rat model of post-traumatic stress...

This study was aimed to investigate the cardiovascular function in rats with post-traumatic stress disorder (PTSD) and the potential association with the activities of the rostral ventrolateral medulla (RVLM) and the medial habenular nucleus (MHb). Multi-channel in vivo recordings were used to simultaneously acquire spontaneous neuronal firing and peripheral physiological indices, and FluoroGold (FG) retrograde tracing technique was used to observe the projections of labeled neurons in the MHb. The results showed that the discharge frequency of RVLM and MHb neurons, the systolic blood pressure (SBP), and the mean arterial pressure (MAP) in the PTSD group were all increased significantly compared with those in control group (P < 0.05). MHb neurons were retrogradely labeled by FG through microinjection (4% FG, 0.5 μL) into the RVLM. In the control group, electrical stimulation in the MHb increased heart rate (HR) at 100-300 μA (P < 0.05), elevated SBP and MAP at 200-300 μA (P < 0.05), and remarkably increased the RVLM neuronal discharge frequency at 100-500 μA (P < 0.05 or P < 0.01). In the PTSD group, however, only the discharge frequency of RVLM neurons was increased by the electrical stimulation at 100-300 μA (P < 0.05). These results suggest that cardiovascular activities of the PTSD model rat are enhanced, and this change may be related to the activity changes of RVLM and MHb and the potential connection between the two nuclei.